This invention relates to an actuator using an elastic extensible member extending in axial directions by either supplying or exhausting a pressurized fluid into and from the elastic extensible member.
Electric motors, hydraulic cylinders and the like have been known as actuators. However, an electric motor usually requires a speed reduction mechanism including gear trains to increase weight and space to be occupied by the actuator and often suffers a limitation of operable range. Moreover, due to the occurence of unavoidable sparks, use of the actuator in an explosion atmosphere is limited.
In contrast herewith, with hydraulic cylinders including motors and cylinders actuated with oil pressure, in addition to the above problems it is difficult to completely prevent leakage of operating oil so that environmental contamination by the leaked oil could not be avoided. Moreover, the temperature and purity of the operating oil must be finely managed and there are many other problems to be solved in management of the hydraulic cylinders.
In addition, in order to obtain an actuator having a high power, it will be unavoidably large sized.